OK, never mind that, it was an unrelated problem. Still, though ShadowHelper completes and though I do
SimpleVector offset = new SimpleVector(1, 0, -1).normalize();
offset.rotateY(0.007f);
projector.lookAt(ground.getTransformedCenter());
projector.setPosition(hero.get(0).getTransformedCenter());
projector.moveCamera(new SimpleVector(0, -1, 0), 200);
projector.moveCamera(offset, 215);
sun.setPosition(projector.getPosition());
sh.updateShadowMap();
sh.drawScene();
before calling buffer.update, I see no shadows being cast.